The influence of atmospheric-induced phase distortion on imaging has traditionally been studied through theoretical determinations of an optical turbulence modulation transfer function (MTF). The MTF for optical turbulence is defined only for very long (i.e., slow) or very fast (i.e., short) exposure time intervals, and is of limited use for real-time simulation of optical turbulence effects on imaging. Typically, digital simulation of optical turbulence effects is accomplished by theoretically estimating the MTF for turbulence, and then multiplying a specialized representation of this MTF with the two-dimensional Fourier transform of an input digital image. The truncated result is then inverse Fourier transformed to show a long-exposure (i.e., blurred) image similar to what would be seen with a long-exposure snapshot. Direct simulation of atmospheric effects on imaging system performance is computationally intense. The ability to simulate the statistical behavior of optical turbulence effects in real-time is a major problem that the present invention solves.
The present invention uses optical techniques, rather than digital techniques, to introduce dynamic spatio-temporal chaotic phase distortions into a computer-generated image. Many of the difficulties associated with digital simulation are overcome by the present invention. The present invention also offers a cost-effective, and efficient, device for and method of determining how imaging systems will operate under realistic atmospheric conditions.
The present invention uses a modified optical kaleidoscope. The conventional optical kaleidoscope was developed under the direction of Prof. Mikhail A. Vorontsov at Moscow State University. The details of the optical kaleidoscope are disclosed in an article by Prof. Vorontsov and A. V. Larichev entitled "Intelligent laser systems: adaptive compensation of phase distortions in nonlinear system with two-dimensional feedback," SPIE Vol. 1409 Nonlinear Optics, 1991, pp. 260-266, and by Prof. Vorontsov, S. A. Akhmanov, V. Yu. Ivanov, A. V. Larichev, and N. I. Zheleznykh in an article entitled "Controlling transverse-wave interactions in nonlinear optics: generation and interaction of spatio-temporal structures," in J. Opt. Soc. Am. B, Vol. 9, No. 1, January 1992, pp. 78-90. The present invention uses a modified optical kaleidoscope that exhibits stronger diffraction in the optical feedback path then does the conventional optical kaleidoscope. The modified optical kaleidoscope enables one to simulate pattern disintegration with the corresponding transition to well-developed spatio-temporal chaos.
U.S. Pat. No. 4,707,077, entitled REAL TIME IMAGE SUBTRACTION WITH A SINGLE LIQUID CRYSTAL LIGHT VALVE, discloses a device for subtracting one image from another image in real time using a liquid-crystal light-valve (LCLV). The present invention adds one image to another image in real time using a LCLV where the added image is a simulation of atmospheric turbulence created by a modified optical kaleidoscope. U.S. Pat. No. 4,707,077 does not disclose a device for adding an image to another image and does not disclose a device for simulating atmospheric turbulence as the present invention does.
U.S. Pat. No. 5,206,674, entitled SYSTEM FOR THE DISPLAY OF IMAGES GIVEN BY A SPATIAL MODULATOR WITH TRANSFER OF ENERGY, discloses a device for displaying an image on a wide screen liquid-crystal video display. The present invention displays an image but not necessarily on a wide-screen display. U.S. Pat. No. 5,206,674 does not disclose a device for adding simulated atmospheric turbulence to an image as the present invention does.
U.S. Pat. No. 5,229,872, entitled EXPOSURE DEVICE INCLUDING AN ELECTRICALLY ALIGNED ELECTRONIC MASK FOR MICROPATTERNING, discloses a device for and method of using a LCLV to direct an electron beam to produce microscopic patterns on a semiconductor substrate. The present invention uses LCLVs to simulate atmospheric turbulence and add said turbulence to another image. U.S. Pat. No. 5,229,872 does not disclose a device for or method of adding simulated atmospheric turbulence to an image as the present invention does.
U.S. Pat. No. 5,083,854, entitled SPATIAL LIGHT MODULATOR WITH IMPROVED APERTURE RATIO, discloses a device for and method of using a LCLV to magnify an image in segments while preserving spatial boundaries between adjacent magnified segments. The present invention uses LCLVs to project images but not to magnify them. U.S. Pat. No. 5,083,854 does not disclose a device for or method of adding simulated atmospheric turbulence to an image as the present invention does.
U.S. Pat. No. 5,071,231, entitled BIDIRECTIONAL SPATIAL LIGHT MODULATOR FOR NEURAL NETWORK COMPUTERS, discloses a device for adding two images. The present invention adds two images where one of the two images is a simulation of atmospheric turbulence. U.S. Pat. No. 5,071,231 does not disclose a device for adding simulated atmospheric turbulence to an image as the present invention does.